Koushirou Saeki  

, 佐伯 耕四郎

At 27 years old, koushirou is a large man with a rarely trimmed beard who works for a company that helps people find partners for marriage. initially, he appears to be reserved and gruff, but in reality, he has strong emotions that he struggles to express eloquently. his protectiveness towards nanoka clashes with his attraction to her and the sexual frustration he feels since their breakup, causing him to sometimes behave brusquely towards her.